885P - Different patterns of treatment failure between p16+ and p16- patients affected by oropharyngeal carcinoma (OPC) undergoing (chemo)radiation

Background

The available data regarding different patterns of recurrence (DPR) between p16+ and p16- OPC patients (pts) are conflicting, and the present study aims at clarifying it.

Methods

We retrospectively collected data on anyT, anyN, M0 OPCs treated with definitive IMRT (66-72 Gy) ± systemic therapy in 14 South-European Centres from 2007 to 2019 evaluating DPR (incidence of distant (DR) and/or locoregional recurrence (LR)) between p16+ and p16- pts and among p16+ subgroups.

Results

We analyzed 674 pts with a median follow-up time of 6 (5.7-6.3) years (CI 95%). The DPR between p16+ and p16- pts are reported in the table. In the p16+ group the incidence of exclusive DR or DR +/- LR was greater than the p16- cohort (38.5% vs 28.4% and 51.3% vs 35.8%), while p16- OPCs experienced more exclusive LR or LR +/- DR (64.2% vs 48.7% and 71.6% vs 61.5%). Subgroup analyses of p16+ OPCs by smoking history (>10 pack-years (PY), 10 PY p16+ pts were included in the analysis. Actually, the proportions of exclusive DR (and DR +/- LR) is greater in the >10 PY p16+ group (43.5% and 58.7%) when compared with

Conclusions

p16- and p16+ OPCs showed DPR after (chemo)radiation, with a higher risk of LR and DR for p16- and p16+ respectively, with potential implications on both the pattern of observation after treatment and the salvageability of clinical failures. Surprisingly, the different behavior of p16+ OPCs is mostly observed in heavy smokers, while oligo/no smokers have a pattern of recurrence more similar to p16- OPCs.

Clinical trial identification

Editorial acknowledgement

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.